Process for producing hectographic prints



United States Patent C) 3,252,412 PROCESS FOR PRODUCING HECTOGRAPHICPRINTS Albert Emiel Van Hoof, Berchem-Antwerp, Belgium,

assignor to Gevaert Photo-Producten N.V., Mortsel- Antwerp, Belgium, acompany of Belgium N Drawing. Filed Oct. 7, 1960, Ser. No. 61,052 Claimspriority, application Netherlands, (let. 8, 1959, 244,134 13 Claims.(Cl. 101149.4)

The present invention relates to the manufacture of a number ofhectographic prints from a photographically obtained matrix.

It is known from the British specification 804,076 (US. Serial No.582,944, filed May 7, 1956, and now abandoned) to obtain tens of printsfrom any original what ever by making a photographic reproduction of theoriginal on light-sensitive material provided with a sliver halideemulsion which contains a preferably at most slightly colored and atmost slightly water-soluble color coupler, wherein by tanningdevelopment the formed image is caused to adhere selectively to thesupport of the photographic material, while the rest of the emulsion isremoved, by bringing the remaining tanned image, containing the colorcoupler, in the presence of a print liquid into contact as master sheetwith a print paper the print paper and/ or print liquid containing meansfor converting the color coupler into dyestulf and/ or to dissolve theformed dyestuff or the color coupler, and by bringing again and againnew print paper into contact with the matrix in the presence of printliquid.

In said British specification (U.S. Serial No. 582,944, filed May 7,1956) as well as in US. patent application Serial No. 37,101, filed June20, 1960, now Patent No. 3,129,097, several methods of embodiment aredescribed for the manufacture of this matrix or relief image.

According to the examples of said British specification (U.S. Serial No.582,944, filed May 7, 1956) the paper on which is to be printed and/orthe print liquid must contain a means for converting the color couplerinto dyestuif very rapidly and at room temperature. If the emulsioncontains a leucobase, an oxidizing agent must be present in the paperand/ or in the print liquid. For this purpose, multivalent cerium-,vanadium-, manganese compounds, dichromates etc. are of particularimportance. Further, the layer of the print paper can contain productssuch as heteropoly acids which increase the light-fastness of theorganic dyestutf.

Finally, the print liquid must be used in such a way that either thecolor coupler in the emulsion or the formed dyestutf be dissolved andcan diffuse to 'the print paper.

An aqueous solution of an acid, preferably an organic acid such asoxalic acid, critric acid, tartaric acid etc. is particularly suited asprint liquid when leucobases are used.

In Example 3 of said British specification (U.S. Serial No. 582,944,filed May 7, 1956) a method is described wherein a gelatin relief,containing both a leucobase and an oxidizing agent, is brought intocontact with ordinary paper in the presence of an aqueous acid solutionwhereby simultaneously the leucobase is converted into the dyestuff, thelatter diffuses over to the paper and gives there in a colored print ofthe original.

Bringing the matrix into contact with the paper can occur in a printingapparatus of the alcohol duplicator type. If in this process an aqueousacid solution is used as print liquid, there is the risk that theconstruction material of the duplicator is affected. Moreover, the papermoistened with aqueous solution remains easily sticked to the imagerelief serving as matrix.

In order to avoid all these drawbacks, the leucobase can first beconverted into a dyestulf after obtaining the 3,252,4l2 Patented May 24,1965 image relief containing said leucobase of a triphenyl methanedyestuff, by one or more bath treatments with an oxidizing agent and adiluted acid-and by making thereafter prints in an ordinary alcoholduplicator by means of the ordinary alcohol duplicator print liquidwhich in most cases contains one or more lower aliphatic alcohols.

The disadvantage of this method, however, is to be found in the rinsingout of the formed dyestuff during the treatment which is necessary forthe conversion of the leucobase into dyestuff so that only a smallnumber of rather unsharp prints is obtained.

It has now been found that a large number of sharp prints can beobtained from an original by using the method of said Britishspecification (U.S. Serial No. 582,944, filed May 7, 1956) by treatingthe formed relief image with an oxidizing agent, an acid and aprecipitating agent for the dyestuff formed by oxidation before printingby means of the alcoholic print liquid.

The new process offers the important advantage that the use of acidsolutions in the alcohol duplicator is omitted avoiding in this way thecorroding action on metal parts.

Another important advantage consists therein that the dissolution of thecolor coupler in the acid bath is considerably counteracted in this way.

As suitable oxidizing agents which can be appliedin the new processmultivalent cerium-, vanadiumand manganese compounds, dichromates etc.are mainly considered.

As suitable acids which can be applied in the new process mineral acidssuch as phosphoric acid, nitric acid, sul-' furic acid, and oragnicacids, such as acetic acid, citric acid, glycolic acid, sulfaminic acidand tartaric acid, are mainly considered.

As precipitating agents for the dyestuffs formed by oxidation which donot or at least little solubilize the latter in aqueous treating baths,those can be chosen which are used for manufacturing pigments and formordanting basic dyestuffs on textile fibers. Some of the mostappropriate representatives are some isoor hetero-poly acids and theirsalts, such as alkaliand ammonium molybdates, -tungstates,phosphomolybdates, phosphotungstates, silicotungstates,phosphomolybdato-tungstates etc. In this respect also some organic acidssuch as dichloro acetic acid, trichloro acetic acid and sulfosalicylicacid offer interesting possibilities for application.

In principle, the treatment of the washed image relief according to themethod of the present invention is carried out in several steps. Thus,the master sheet can first be led through an oxidizing bath consistingof a diluted aqueous potassium permanganate solution and next through anacid bath consisting of an aqueous diluted acid wherein theprecipitating agent is dissolved for the triphenyl methane dyestuifformed by oxidation. This precipitating agent, however, can also bedissolved in the oxidizing bath.

Another embodiment of the process according to the present inventionconsists therein that the washed image relief after treatment with anoxidizing agent is immersed in an acid solution the acid of which servesitself as precipitating agent of the dyestuif such as for instancetrichloroacetic acid.

A further and particular simple embodiment of the process according tothe present invention consists therein that the washed image relief istreated with only one solution which besides the oxidizing agent alsocontains a precipitating acid. Instead of an acid which serves asprecipitating agent for the dyestutf, also a combination of anon-precipitating acid and a precipitating agent can be chosen.Evidently, the acid must at least for some tim be compatible with theoxidizing agent.

After this treatment the obtained mastersheet can be used, after removalof the excess of liquid, for manufacturing some tens of prints ontopaper which was moistened with a print liquid mainly consisting of alower aliphatic alcohol such as methanol, ethanol or isopropanol or of amixture of such alcohols either mutually or with water. This printliquid can evidently also contain the usual ingredients for composingduplicator liquids. Such compositions are i.-a. described in J. Chem.Education, 32, 200-202 (1955) and in the American patent specifications2,228,108, 2,262,488 and 2,294,711.

The following examples illustrate the invention without limiting,however, the scope thereof.

Example 1 A material manufactured as described in British specificationNo. 804,076 (U.S. Serial No. 582,944, filed May 7, 1956) isreflectographically exposed through an original. After hardeningdevelopment according to the above US. application Serial No. 37,101,filed June 20, 1960, the non-developed and consequently non-tanned partsof the gelatin emulsion layer are washed away. The image relief thusobtained is immersed for seconds in a 1% aqueous potassium permanganatesolution whereafter the excess of solution is removed by squeezingbetween two rubber rollers. This image relief is then immersed for 5seconds into a 1% aqueous trichloroacetic acid solution. The excess ofliquid is then removed by squeezing between two rollers whereafter themaster sheet obtained is fixed on a duplicator containing isopropanol asprint liquid. With this master sheet tens of sharp prints of theoriginal to be reproduced are obtained.

Example 2 A gelatin relief image obtained and soaked with a potassiumpermanganate solution as in the foregoing example but containing leucocrystal violet instead of leuco malachite green, is immersed for 15seconds, after removal of the excess of solution with blotting paper, ina solution of the following composition:

Cm. 20% aqueous citric acid 50 aqueous silicotungstic acid 5 Furthertreatment as in Example 1 and printing with a print liquid of thefollowing composition: ethanol 80%, methanol 18% and methyl glycol 2%.Tens of sharp prints of the original are obtained.

Example 4 A gelatin relief image obtained as in Example 3 is immersedfor seconds in a 2.5% aqueous ammonium dichromate solution. Afterremoval of the excess of solution, the relief image is immersed for 15seconds into a solution consisting of:

cm aqueous tartaric acid 5O 10% aqueous silicotungstic acid 3 Furthertreatment and printing as in Example 1 gives tens of sharp prints of theoriginal.

Example 5 A gelatin relief image is obtained and soaked with a potassiumpermanganate solution as in Example 3 and the excess of liquid is,removed by squeezing between two rubber rollers. Next, the relief imageis immersed into a solution of the following composition:

Cm. 20% aqueous tartaric acid 50 10% aqueous sodium phosphomolybdate 5Further treatment and printing as in Example 2 gives tens of sharpprints of'the original.

Example 6 A gelatin relief image obtained as described in Example 3 isimmersed for 5 seconds into a solution of the following composition:

After removal of the excess of liquid by squeezing between two rubberrollers, tens of prints of the original are obtained as in Example 3.

Example 7 A gelatin relief image obtained as in Example 1. is immersedfor seconds into a solution of the following composition:

Cm. 10% aqueous ammonium dichromate 4 20% aqueous trichloro acetic acidFurther treatment as in Example 3.

Example 8 A gelatin relief image obtained as in Example 1 is immersedfor 3 seconds into a mixture consisting of 20 cm. of 20% aqueoustrichloroacetic acid and 50 cm. of a solution of the followingcomposition Cerium (IV)-sulfate, g. Concentrated sulfuric acid, cm. 28Water, cm. 500

Further treatment as in Example 3.

Example 9 A gelatin relief image obtained as in Example 1 is immersedfor 15 seconds into a solution of the following composition:

Cm. 3% aqueous potassium permanganate 40 Glacial acetic acid 40 10%aqueous ammonium molybdate 40 Further treatment as in Example 3. Iclaim: 1. In a method of making multiple prints of a printing master ina spirit duplication process wherein:

(A) Said master is prepared by the steps of (1) Exposing to anindicia-bearing original to be copied a light-sensitive photographicmaterial including a support bearing a silver halide emulsion layercontaining a finely-divided, water-insoluble, potential color-formingleucobase of a triphenylmethane dyestuff, Subjecting the exposedphotographic material to tanning development to form in said emulsionlayer a positive latent mirror image of said original and harden theareas of said layer bearing said latent mirror image, Removing theunhardened areas of said layer -to leave a positive relief mirror imageof hardened emulsion attached to said support, and Subjecting thematerial from step (3) to oxidation and acidification to convert saidleucobase to a colored dyestulf; and (B) Prints are made from saidmaster'resulting from (A) by pressing into contact therewith printpaper;

moistened with an alcoholic print liquid comprising essentially analcohol selected from the group consisting of methanol, ethanol,isopropanol and their mixtures; in combination, the improvement ofcontacting the positive relief mirror image prior to said print-makingstep (B) with an aqueous solution of a basic dyestuff mordanting agentto precipitate the colored dyestuif in the hardened areas of saidemulsion layer.

2. The method of claim 1 wherein said relief image is contacted withsaid solution of said mordanting agent by immersing the image in saidsolution for a time of about 3-30 seconds and thereafter removing excesssolution therefrom.

3. The method of claim 1 wherein said positive relief mirror image iscontacted with an aqueous solution of a material selected from the groupconsisting of the isopoly acids, the heteropoly acids, and their alkaliand ammonium salts.

4. The method of claim 1 wherein said material from step 3 is acidifiedby treatment with an aqueous solution of a weak organic acid.

5. The method of claim 1 wherein said triphenylmethane dyestuff ismalachite green.

6. The method of claim 1 wherein said triphenylmethane dyestuft' iscrystal violet.

'7. The method of claim 1 wherein said leuco-base of said dyestuff isoxidized by treatment with an aqueous solution of potassiumpermanganate.

8. The method of claim 1 wherein said leucobase of said dyestutf isoxidized by treatment with an aqueous solution of ammonium'bichromate.

9. The method of claim 1 wherein said leucobase of said dyestuif isoxidized by treatment with an aqueous tion of a material selected fromthe group consisting of molybdic acid and tungstic acid, the complexesof such acids with phosphorus and silicon, and the alkali metal andammonium salts of said acids and said complexes.

11. The method of claim 10 wherein said material is molybdic acid.

12. The method of claim 10 wherein said material is tungstic acid.

13. The method of claim 1 wherein said acidification and precipitationare effected simultaneously by treatment of said relief image with anaqueous solution of a material of the group consisting ofdichloroiacetic acid, trichloroacetic acid and sulfosalicylic acid.

References Cited by the Examiner UNITED STATES PATENTS 1,923,625 8/1933Jackson 101-1494 1,935,477 11/1933 Martinez -93 2,034,220 3/1936 Allison96-72 2,054,261 9/1936 Lierg 9635 2,266,456 12/1941 Wilder 9621 X2,855,300 10/1958 Chalkley 9690 X 2,898,852 8/1959 Staehle et a1 96-283,049,994 8/1962 Raczynski et al. 101149.5 3,096,711 7/1963 Ritzerfeldet a1. 101--149.4 3,152,898 10/1964 Hepher 96-33 X FOREIGN PATENTS539,781 9/1941 Great Britain.

OTHER REFERENCES Glafkides, Photographic Chemistry, 1960, vol. 2,Fountain Press, London, page 713.

ALEXANDER D. RICCI, Primary Examiner.

MILTON STERMAN, Examiner.

1. IN A METHOF OF MAKING MULTIPLE PRINTS OF A PRINTING MATER IN A SPIRITDUPLICATION PROCESS WHEREIN: (A) SAID MASTER IS PREPARED BY THE STEPS OF(1) EXPOSING TO AN INDICIA-BEARING ORIGINAL TO BE COPIED ALIGHT-SENSITIVE PHOTOGRAPHIC MATERIAL INCLUDING A SUPPORT BEARING ASILVER HALIDE EMULSION LAYER CONTAINING A FINELY-DIVIDED,WATER-INSOLUBLE, POTENTIAL COLOR-FORMING LEUCOBASE OF A TRIPHENYLMETHANEDYESTUFF, (2) SUBJECTING THE EXPOSED PHOTOGRAPHIC MATERIAL TO TANNINGDEVELOPMENT TO FORM IN SAID EMULSION LAYER A POSITIVE LATENT MIRRORIMAGE OF SAID ORIGINAL AND HARDEN THE AREAS OF SAID LAYER BEARING SAIDLATENT MIRROR IMAGE, (3) REMOVING THE UNHARDENED AREAS OF SAID LAYER TOLEAVE A POSITIVE RELIEF MIRROR IMAGE OF HARDENED EMULSION ATTACHED TOSAID SUPPORT, AND (4) SUBJECTING THE MATERIAL FROM STEP (3) TO OXIDATIONAND ACIDIFICATION TO CONVERT SAID LEUCOBASE TO A COLORED DYESTUFF; AND(A) BY PRESSING ITO CONTACT THEREWITH PRINT PAPER MOISTENED WITH ANALCOHOLIC PRINT LIQUID COMPRISING ESSENTIALLY AN ALCOHOL SELECTED FROMTHE GRUOP CONSISTING OF METHANOL, EHTANOL, ISOPROPANOL AND THEIRMIXTURES; IN COMBINATION, THE IMPROVEMENT OF CONTACTING THE POSITIVERELIEF MIRROR IMAGE PRIOR TO SAID PRINT-MAKING STEP (B) WITH AN AQUEOUSSOLUTION OF A BASIC DYESTUFF MORDANTING AGENT TO PRECIPITATE THE COLOREDDYESTUFF IN THE HARDENED AREAS OF SAID EMULSION LAYER.